Kyoto's Caps on Emissions
Hit Snag in Marketplace

U.N. Mulls How to Fix
Pollution-Credit System;
'Expecting Too Much'

The Kyoto Protocol was supposed to harness market forces to solve global warming. It slapped caps on greenhouse-gas emissions and set up a complex market for companies to trade permits to pollute.

But it hasn't yet ignited the green-energy revolution its architects were expecting. The cap-and-trade system has brought about useful projects targeting a few especially potent greenhouse gases. It hasn't, however, forced the industrialized world to meaningfully curb what scientists say is the biggest problem of all -- the growing...